Depends on the community culture and what they perceive as outsider behaviour. e.g. A protestant might not be welcomed in a catholic neighborhood.

But isn't "outgroup members are not welcome" the definition of (mild) xenophobia? Indeed, religious disagreements are a major source of it.

I'm just confused. I thought they're the same thing.

One is proactive assessment by a community, the other is blind bigotry against outsiders. The inclusion of bigotry as a deciding component is the key, IMHO.

One wants to proactively stop outsiders from joining their community. The other stops outsiders from joining their community using bigotry? Can you see why I'm confused?

No. I may be seeing an argument of semantic similarity, but the inclusion of bigotry is the defining factor of xenophobia. Closing down a community can be due to other drivers beyond fear of outsiders.